Some insects are virulent and can cause harm, such as skin irritation, infection, and even disease, to people. In order to protect ourselves from such insects, various types of products have been developed. These products are developed to kill, suppress reproduction or proliferation, and debilitate sensory organs to maim perception.
Among these developed products, debilitation of sensory organs is used for a “repellent.” In particular, the repellent is often used for protecting ourselves from mosquitoes. Such a mosquito repellent can paralyze sensory organs of a mosquito and prevent the mosquito from tracing carbon dioxide or odors generated from the skin of a mammal, such as human beings.
Mosquito is a very harmful insect in view of hygiene since it can carry dangerous pathogens for causing disease such as dengue, yellow fever, encephalitis, and malaria. Considering that millions of people die worldwide every year from malaria, it is difficult to ignore the fact that mosquito is a deadly, harmful insect. It is reported that malaria has resurfaced. The number of malaria cases and areas of malaria occurrences have rapidly increased in recent years. Likewise, the number of malaria infected patients has recently increased to reach several thousand patients every year in Korea alone. Notably, the infection rate of malaria has increased every year and as can be inferred from the discussion above, direct or indirect contact with mosquitoes can have potentially dangerous consequence.
To combat mosquitoes, a mosquito repellent is preferably used because it is relatively free from harm to a human body, compared to other mosquito-control methods that mostly use toxic pesticides. At present, various mosquito repellents are available for public. In particular, N,N-diethyl-m-toluamide (DEET) has been the most widely used owing to its excellent mosquito repellent effect. However, since the DEET has an unpleasant odor and strong penetration into the skin, which would be potentially harmful to human, the use of DEET has been restricted from application on children, pregnant women, nursing mothers, hypotensive patients, people with sensitive skin, and so on. Currently, the United States restricts mosquito repellents containing more than 20% DEET from being manufactured for public use.
In view of this, many efforts have been made to replace DEET. Although it is known that citronella, linalool, and lemongrass have repellent activities against mosquitoes, they are less effective than DEET. Due to the low repellent activities, practical use of these materials such as citronella, linalool, and lemongrass for repelling mosquitoes has been restricted.
U.S. Pat. No. 6,811,789 discloses a fragrant composition having a mosquito-repelling effect, which comprises a mixture made of isomenthone, linalool, geraniol, cirtal and citronellol as effective ingredients, wherein the mixture further comprises a fatty acid having 8 to 10 carbon atoms. This composition must contain multiple compounds as an effective mosquito-repelling ingredient and the composition represents repelling effect just equal to the effect of DEET.
Accordingly, tremendous efforts have been made to develop new mosquito repellents derived from natural resources, having more excellent repelling effect than DEET.